Glass capillary column gas chromatography of barbiturates after flash-heater derivatization with dimethylformamide dimethylacetal.

Glass capillary column gas chromatography has been used for quantitative and qualitative analyses of barbiturates. The barbiturates are first converted into the corresponding acetal derivates by flash-heater derivatization, using dimethylformamide dimethylacetal as the derivatization reagent. The influence of the injection port temperature, the column temperature, the solvent used to dissolve the substances and the reagent dilution were studied in order to obtain the optimal response with good reproducibility. Calibration graphs in the concentration range 5--50 micrograms/ml were evaluated and the relative standard deviations for the quantitative analyses were calculated. High sensitivity was obtained when extracts from plasma containing phenobarbital in the low therapeutic concentration range were analysed using the described derivatization technique.